As an electrically rewritable nonvolatile memory having a large capacity, a flash memory has heretofore been well known. The large capacity of the flash memory has been realized by microfabrication, but it is considered that it will be difficult to attain a larger capacity due to a limit of the microfabrication. Meanwhile, as a replacement for the flash memory, a resistive RAM using a variable resistance element has been proposed. It is possible to configure the resistive RAM by using a so-called crosspoint memory in which the variable resistance element is disposed at an intersection of a bit line and a word line. Therefore, the resistive RAM has the advantage of a larger capacity enabled by a three-dimensional structure which is attained due to easy layer structure formation.
As the types of the variable resistance elements, a phase change RAM (hereinafter referred to as PRAM), the resistive RAM (hereinafter referred to as ReRAM) using an oxide, an electrochemical metallization memory (hereinafter referred to as ECM), and the like have been known. Examples of the ECM include a memory (amorphous Si memory; hereinafter referred to as a-Si memory) using amorphous silicon and the like.